On Wed, May 18, 2022 at 05:14:49PM -0700, Eric Biggers wrote: > On Wed, May 18, 2022 at 10:11:31AM -0700, Keith Busch wrote: > > diff --git a/block/fops.c b/block/fops.c > > index b9b83030e0df..d8537c29602f 100644 > > --- a/block/fops.c > > +++ b/block/fops.c > > @@ -54,8 +54,9 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, > > struct bio bio; > > ssize_t ret; > > > > - if ((pos | iov_iter_alignment(iter)) & > > - (bdev_logical_block_size(bdev) - 1)) > > + if ((pos | iov_iter_count(iter)) & (bdev_logical_block_size(bdev) - 1)) > > + return -EINVAL; > > + if (iov_iter_alignment(iter) & bdev_dma_alignment(bdev)) > > return -EINVAL; > > The block layer makes a lot of assumptions that bios can be split at any bvec > boundary. With this patch, bios whose length isn't a multiple of the logical > block size can be generated by splitting, which isn't valid. How? This patch ensures every segment is block size aligned. We can always split a bio in the middle of a bvec for any lower level hardware constraints, and I'm not finding any splitting criteria that would try to break a bio on a non-block aligned boundary. > Also some devices aren't compatible with logical blocks spanning bdevs at all. > dm-crypt errors out in this case, for example. I'm sorry, but I am not understanding this.
